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10 Immunology
Pages 156-170

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From page 156...
... In spaceflight as on Earth, the immune system interacts dynamically with other body systems. Factors that must be considered during spaceflight include changes induced by microgravity; changes induced in the neuroendocrine stress hormone system and other stress responses; and changes induced by exposure to radiation, by alterations in nutritional intake, by alterations in levels of 1,25-dihydroxyvitamin D3 (i.e., changes in calcium)
From page 157...
... ~3 Studies on antibody responses, mechanistic studies, and studies to determine the biological and biomedical significance of spaceflight-induced alterations in immunological parameters have been few in number and limited in scope, owing primarily to technical difficulties in carrying out experiments and not to lack of interest or potential effects. Most spaceflight studies conducted with animals have involved specimens shared by multiple research groups in different disciplines.
From page 158...
... The response to colony stimulating factors of bone marrow cells from rats flown on several Russian Cosmos biosatellite missions has been examined.45 46 The response of cells from rats flown in space to both granulocyte-macrophage colony stimulating factor and macrophage colony stimulating factor was greatly reduced after spaceflight, compared with the response of cells from control animals housed in normal caging or in caging designed to simulate conditions in the space capsule.47 48 Some alterations in leukocyte subset distribution were also noted after spaceflight of rats on the Cosmos capsule and the space shuttle, most notably an increase in the level of CD4+ helper T cells.49~52 lh~s was the t~rst ~n-ll~ght an~mal study.
From page 159...
... One reason that this issue has not been addressed before is that animals have had to be shared among investigators in multiple disciplines, and so carrying out functional immunological studies could affect the results of other investigators in other disciplines. It is hoped that research in the International Space Station era will allow assignment of specific animals for these important immunological studies.
From page 160...
... Changes observed in cells obtained from cosmonauts immediately after Russian short-term flights include decreases in natural killer cell activity and decreases in production of interferon-oc/,8.6~~63 Interestingly, the decreased interferon-oc/,8 production was from the same mission and the same cosmonauts whose peripheral blood leukocytes were placed in culture and challenged with an interferon inducer in the in vitro space experiment of Talas et al., in which interferon-oc/,8 production was markedly enhanced.64 These results reiterate the point that in vitro spaceflight results may not be representative of the in vivo situation, because cells in culture are not in their normal environment involving interactions with other body systems. When testing was carried out on samples from cosmonauts immediately upon their return to Earth after long-duration spaceflight, the most prominent effects were alterations in natural killer cell activity, alterations in leukocyte blastogenesis, and alterations in interleukin-2 production.65 66 The same studies also
From page 161...
... These results were originally reported with data obtained from astronauts during relatively short-term space shuttle flight69 but have been extended to longer-term Mir space station experiments.70 These experiments involved delayed hypersensitivity skin testing to common recall antigens and did show an effect of spaceflight. There was a marked decrease in the skin-test response to these antigens when the crews were tested during snacefli~ht.
From page 162...
... Models that have been used include hindlimb unloading in rodents,9~~93 chronic bed rest in humans,94~96 and rotation of cells in a clinostat.97 Hindlimb unloading of rodents has been used to simulate some aspects of the effects of microgravity on immune responses.98 Two different varieties of the model have been used: suspension by the tail and harness suspension.99 There are benefits and drawbacks to both varieties of the model; however, studies with both involving immune responses have shown similar results to date.~00~~05 Suspension of rats and mice with no load bearing on the hindlimbs and with head-down tilt (usually 15° to 20°) leads to bone and muscle disuse and a fluid shift to the head.
From page 163...
... can be used as a control for the stress of the model. Hindlimb unloading with a head-down tilt in rats has been shown to yield changes in several dynamic immune parameters, but to have little to no effect on more static immune parameters.~06~07 Immune parameters altered after hindlimb unloading with a head-down tilt of rodents have included interferon-oc/,8 and -fly production, the response of bone marrow cells from suspended rats to exogenous colony stimulating factors, macrophage function, and interleukin production.~°~~~ There was no correlation between corticosterone levels and alterations in immune responses.
From page 164...
... 1996. Effects of spaceflight on rat peripheral blood leukocytes and bone marrow progenitor cells.
From page 165...
... 1996. Effects of spaceflight on rat peripheral blood leukocytes and bone marrow progenitor cells.
From page 166...
... 1992. Cytokine secretion by immune cells in space.
From page 167...
... 1992. Spaceflight alters immune cell function and distribution.
From page 168...
... 1994. Influence of antiorthostatic suspension on resistance to murine Listeria monocytogenes infection.
From page 169...
... PART III Additional Space Environment Issues


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